Structural and electrical characterization of hybrid metal-polypyrrole nanowires

We present here the synthesis and structural characterization of hybrid Au-polypyrrole-Au and Pt- polypyrrole-Au nanowires together with a study of their electrical properties from room-temperature down to very low temperature. A careful characterization of the metal-polymer interfaces by trans- mission electron microscopy revealed that the structure and mechanical strength of bottom and upper interfaces are very different. Variable temperature electrical transport measurements were performed on both multiple nanowires - contained within the polycarbonate template - and single nanowires. Our data show that the three-dimensional Mott variable-range-hopping model provides a complete framework for the understanding of transport in PPy nanowires, including non-linear current-voltage characteristics and magnetotransport at low temperatures.Comment: Phys. Rev. B Vol. 76 Issue 11 (2007

Maximizing rehabilitation outcomes in geriatric hip fracture patients: the impact of surgical variables

Background and aim: Hip fracture is a major traumatic event with high mortality and disability rate. Its management in the acute setting and in the rehabilitation process is highly debated. This study evaluates the possible determinants of hip fracture rehabilitation outcome, among which surgical intervention type, weight-bearing status and hospitalization length Methods: The data of 738 hip fracture patients, who completed rehabilitation process in our centre, were collected and patients' functional abilities at the time of admission and discharge were analysed. Results: It has been observed that functional recovery depends on several factors: the type of surgery, the post-operative course and related complications, the hospitalisation time, the surgeon's techniques and expertise and the Orthopaedics centre where the operation is performed. Conclusions: In conclusion, data integration in perspective of an individualised rehabilitation program appears crucial for the functional recovery of the hip fracture patient

Revised and extended analysis in four times ionized xenon Xe V

The atomic-emission spectrum of four times ionized xenon (Xe V) has been observed in the region 500–6700 Å; 233 lines were classified as transition between 5s5p3, 5s25p5d, 5s25p6s with 5s25p2, 5s25p6p and 5s25p4f configurations. Ninty-seven of these lines are reported for the first time. Two new energy level values corresponding to the 5s25p4f configuration have been determined, and we proposed two new values for the previously reported 3D1 and 3G5 energy levels of this configuration. The value of the 5s25p6p 1S0 energy level has also been determined, and we propose a new value for the previously reported 5s25p5d 3F4 energy level. New adjusted values for the previously known levels of the studied configurations are included. Least-squares fitted parametric calculations involving configuration interactions have been carried out to interpret the observed spectrum.Facultad de Ciencias ExactasCentro de Investigaciones Óptica

Revised and extended analysis in four times ionized xenon Xe V

The atomic-emission spectrum of four times ionized xenon (Xe V) has been observed in the region 500–6700 Å; 233 lines were classified as transition between 5s5p3, 5s25p5d, 5s25p6s with 5s25p2, 5s25p6p and 5s25p4f configurations. Ninty-seven of these lines are reported for the first time. Two new energy level values corresponding to the 5s25p4f configuration have been determined, and we proposed two new values for the previously reported 3D1 and 3G5 energy levels of this configuration. The value of the 5s25p6p 1S0 energy level has also been determined, and we propose a new value for the previously reported 5s25p5d 3F4 energy level. New adjusted values for the previously known levels of the studied configurations are included. Least-squares fitted parametric calculations involving configuration interactions have been carried out to interpret the observed spectrum.Facultad de Ciencias ExactasCentro de Investigaciones Óptica

Pinning of quantized vortices in helium drop by dopant atoms and molecules

Using a density functional method, we investigate the properties of liquid 4He droplets doped with atoms (Ne and Xe) and molecules (SF_6 and HCN). We consider the case of droplets having a quantized vortex pinned to the dopant. A liquid drop formula is proposed that accurately describes the total energy of the complex and allows one to extrapolate the density functional results to large N. For a given impurity, we find that the formation of a dopant+vortex+4He_N complex is energetically favored below a critical size N_cr. Our result support the possibility to observe quantized vortices in helium droplets by means of spectroscopic techniques.Comment: Typeset using Revtex, 3 pages and 5 figures (4 Postscript, 1 jpeg

Collective Autoionization in Multiply-Excited Systems: A novel ionization process observed in Helium Nanodroplets

Free electron lasers (FELs) offer the unprecedented capability to study reaction dynamics and image the structure of complex systems. When multiple photons are absorbed in complex systems, a plasma-like state is formed where many atoms are ionized on a femtosecond timescale. If multiphoton absorption is resonantly-enhanced, the system becomes electronically-excited prior to plasma formation, with subsequent decay paths which have been scarcely investigated to date. Here, we show using helium nanodroplets as an example that these systems can decay by a new type of process, named collective autoionization. In addition, we show that this process is surprisingly efficient, leading to ion abundances much greater than that of direct single-photon ionization. This novel collective ionization process is expected to be important in many other complex systems, e.g. macromolecules and nanoparticles, exposed to high intensity radiation fields

Observation and Control of Laser-Enabled Auger Decay

Single photon laser enabled Auger decay (spLEAD) has been redicted theoretically [Phys. Rev. Lett. 111, 083004 (2013)] and here we report its first experimental observation in neon. Using coherent, bichromatic free-electron laser pulses, we have detected the process and coherently controlled the angular distribution of the emitted electrons by varying the phase difference between the two laser fields. Since spLEAD is highly sensitive to electron correlation, this is a promising method for probing both correlation and ultrafast hole migration in more complex systems.Comment: 5 pages, 3 figure

Real-time dynamics of the formation of hydrated electrons upon irradiation of water clusters with extreme ultraviolet light

Free electrons in a polar liquid can form a bound state via interaction with the molecular environment. This so-called hydrated electron state in water is of fundamental importance e.g.~in cellular biology or radiation chemistry. Hydrated electrons are highly reactive radicals that can either directly interact with DNA or enzymes, or form highly excited hydrogen (H∗) after being captured by protons. Here, we investigate the formation of the hydrated electron in real-time employing XUV femtosecond pulses from a free electron laser, in this way observing the initial steps of the hydration process. Using time-resolved photoelectron spectroscopy we find formation timescales in the low picosecond range and resolve the prominent dynamics of forming excited hydrogen states

A quantitative map of nuclear pore assembly reveals two distinct mechanisms

Understanding how the nuclear pore complex (NPC) assembles is of fundamental importance to grasp the mechanisms behind its essential function and understand its role during evolution of eukaryotes1–4. While we know that at least two NPC assembly pathways exist, one during exit from mitosis and one during nuclear growth in interphase, we currently lack a quantitative map of their molecular events. Here, we use fluorescence correlation spectroscopy (FCS) calibrated live imaging of endogenously fluorescently-tagged nucleoporins to map the changes in composition and stoichiometry of seven major modules of the human NPC during its assembly in single dividing cells. This systematic quantitative map reveals that the two assembly pathways employ strikingly different molecular mechanisms, inverting the order of addition of two large structural components, the central ring complex and nuclear filaments. Our dynamic stoichiometry data allows us to perform the first computational simulation that predicts the structure of postmitotic NPC assembly intermediates